U.S. patent number 5,747,775 [Application Number 08/436,453] was granted by the patent office on 1998-05-05 for high speed oven.
This patent grant is currently assigned to Fujimak Corporation. Invention is credited to Hiroshi Matsuo, Hideki Tsukamoto, Akio Ueoka.
United States Patent |
5,747,775 |
Tsukamoto , et al. |
May 5, 1998 |
High speed oven
Abstract
A heating apparatus of the present invention relates to a high
speed oven having a turntable mechanism for heating food products
by utilizing a combination of jet impingement of heated air (a jet
impingement) and microwaves or either of them, the apparatus
comprising a safety device and an exhaust device. This invention
has the following configurations: a turntable mechanism for
enabling the turntable to be preferably rotated, the turntable
including openings at the central part thereof so that the heated
air and microwaves can pass therethrough; a limiter mechanism for
removing overload imposed on the turntable by utilizing only a
mechanical operation; an apparatus provided with scarfed areas on
upper and lower boards of the heating chamber so that the food
products can be baked uniformly even when utilizing a jet
impingement technique; a fan guard comprising a switch activation
means for activating a switch for allowing a generation of the
heated air, which switch is positioned at the outside of the
heating chamber, only when the fan guard is fixed to the heating
chamber; a heating apparatus which simplifies operations for
connecting exhaust tubes upon a number of apparatuses being stacked
on each other; and a turntable driving mechanism for preventing
contaminants from flowing into a gap between a connecting shaft and
an axis receptor.
Inventors: |
Tsukamoto; Hideki (Tokyo,
JP), Ueoka; Akio (Tokyo, JP), Matsuo;
Hiroshi (Tokyo, JP) |
Assignee: |
Fujimak Corporation (Tokyo,
JP)
|
Family
ID: |
27550603 |
Appl.
No.: |
08/436,453 |
Filed: |
May 22, 1995 |
PCT
Filed: |
October 13, 1994 |
PCT No.: |
PCT/JP94/01710 |
371
Date: |
May 22, 1995 |
102(e)
Date: |
May 22, 1995 |
PCT
Pub. No.: |
WO95/10788 |
PCT
Pub. Date: |
April 20, 1995 |
Foreign Application Priority Data
|
|
|
|
|
Oct 14, 1993 [JP] |
|
|
5-055564 U |
Oct 14, 1993 [JP] |
|
|
5-055630 U |
Oct 14, 1993 [JP] |
|
|
5-256726 |
Oct 14, 1993 [JP] |
|
|
5-256727 |
Oct 14, 1993 [JP] |
|
|
5-257258 |
Sep 5, 1994 [JP] |
|
|
6-210961 |
|
Current U.S.
Class: |
219/400; 200/333;
200/43.19; 99/476 |
Current CPC
Class: |
A21B
1/245 (20130101); A21B 1/44 (20130101); H05B
6/6411 (20130101); H05B 6/6473 (20130101) |
Current International
Class: |
F24C
15/32 (20060101); H05B 6/80 (20060101); F24L
015/36 () |
Field of
Search: |
;219/400
;200/43.01,43.02,43.19,333 ;126/21A ;99/474-476 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
|
|
|
|
|
|
|
49-129241 |
|
Dec 1974 |
|
JP |
|
50-132752 |
|
Oct 1975 |
|
JP |
|
52-9147 |
|
Jan 1977 |
|
JP |
|
52-136259 |
|
Oct 1977 |
|
JP |
|
53-128464 |
|
Oct 1978 |
|
JP |
|
55-22094 |
|
Feb 1980 |
|
JP |
|
55-106024 |
|
Jul 1980 |
|
JP |
|
56-138622 |
|
Oct 1981 |
|
JP |
|
61-24820 |
|
Sep 1984 |
|
JP |
|
63-34427 |
|
Feb 1988 |
|
JP |
|
63-210534 |
|
Sep 1988 |
|
JP |
|
63-263326 |
|
Oct 1988 |
|
JP |
|
Primary Examiner: Walberg; Teresa J.
Assistant Examiner: Pelham; J.
Attorney, Agent or Firm: Evenson, McKeown, Edwards &
Lenahan, PLLC
Claims
What is claimed is:
1. A fan guard removably fixed to an inside of a heating chamber,
in front of a means for generating heated air which is to be
transmitted into the inside of the heating chamber, comprising:
a switch activation means for activating a means, positioned at an
outside of the heating chamber, for allowing generation of the
heated air when said fan guard is fixed to the heating chamber,
said switch activation means constituting a part of a means for
fixing the fan guard to the heating chamber,
said switch activation means being adapted to be engaged with an
attachment place provided on a corresponding position on a wall
surface of the heating chamber,
said means for allowing generation of the heated air being disposed
at a position at the outside of the heating chamber corresponding
to said corresponding position of said attachment place.
2. The fan guard according to claim 1, wherein said switch
activation means comprises a magnet, and said means for allowing
generation of the heated air is a magnet closing switch.
3. The fan guard according to claim 2, and further comprising a
means for cooling an area around said magnet closing switch.
Description
BACKGROUND OF THE INVENTION
The present invention relates to a heating apparatus, and more
particularly to a high speed oven having a turntable mechanism, for
heating food products to be cooked by utilizing a combination of
impingement of heated air (a jet impingement) and microwaves or
either of them, the heating apparatus comprising a safety device
and an exhaust system.
DESCRIPTION OF THE PRIOR ART
Though attempts have been made in the past to improve the cooking
oven, there still remains a lot of problems to be solved. Regarding
the cooking oven, in particular one for use both in business and in
homes, there has been a strong demand for a cooking apparatus which
enables the time needed for cooking to be shortened and maintains
and improves delicate cooking qualities of baked products, such as
temperature, baking color, flavor, smell, and so on.
A microwave oven utilizing inductive heating generated by a
microwave can raise the temperature inside the food products in a
short time, so that the time needed for cooking can be shortened.
However, the cooking qualities, such as finish, baking color,
flavor, and smell of the food products are not good. Accordingly,
the microwave oven may, in practice, be regularly used for
re-heating and thawing of the food products, but only rarely used
for the final cooking stage of the baked products.
To overcome the above drawback in the microwave oven, there is an
oven in which inside heating and surface heating are combined, that
is, while the inside of the food is heated with microwaves, its
surface is heated by air convection at a high temperature and
radiation of infrared rays, the oven further comprising a turntable
mechanism on which the food product can be mounted, so that it can
be heated more uniformly. However, the balance of the cooking
finish of the food product may be lost, because the velocity needed
to accomplish the inside heating with microwaves is slower than
that needed to accomplish the surface heating. As a result, if a
heating velocity is adjusted to the cooking finish for the surface
heating, the inside of the food will be heated too much, and thus
the food may be too tough and savory water and juice will be
removed from the food. As a result, the time needed for cooking
will not be shortened very much. On the other hand, if the heating
velocity is adjusted to the time needed for raising the temperature
of the inside of food product, all of the surface may not be
sufficiently heated. Thus, although the cooking time can be made
shorter, the quality of the food can not be maintained.
To solve these above problems, Mr. Donald Paul Smith, an American,
invented an apparatus in which air at a high temperature is ejected
from a plurality of small holes separated from each other to
impinge the air onto the upper and lower surfaces of the food
product, so that the surfaces can be heated at a rate two or four
times faster than a conventionally used forced convection heat
transfer apparatus, it being possible for the apparatus to utilize
microwaves for the inside heating of the food product (U.S. Pat.
No. 3,884,213). The heating principle and method invented by Mr.
Smith are very effective, enabling the time needed for cooking to
be shortened and cooking quality to be improved. However, such an
apparatus having, in practice, the above benefits has not yet
appeared in the market.
The reason for this is as follows. Although the above apparatus can
be used as an apparatus for all baking dishes for all the dry-types
of heating, such as baking, boiling, barbecuing, griddling,
roasting, and fry cooking not using oil, oils and juices might be
dispersed in the oven at the time of cooking depending on the kind
of cooking method and the food product to be cooked. As a result,
these oils and juices would be baked, carbonized and finally
accumulated on wall surfaces and many portions in the oven due to
the high temperature. This would cause many troubles, for example,
a locking of the removable portions in the oven and a local heating
resulting from a generation of microwave sparks. Accordingly, the
level of the cleaning performance on the inside of the oven is very
important for the above type of oven. However, even if the cleaning
performance of the apparatus is improved, providing of such
elements as the jet impingement mechanism, a microwave mechanism
and a turntable makes the structure of the apparatus complicated,
thus making the cleaning performance ineffective. Accordingly, such
an apparatus as that of the present invention has been desired.
In almost all of the prior ovens each comprising a turntable, a
driving device is mounted on the backside of the bottom surface of
the heating chamber, the axis of which device penetrates the bottom
surface of the heating chamber. In such apparatuses as above
constructed, since the driving device might be immersed into oil
and cleaning fluid via its axis receptor, significant
disadvantages, such as a sufficient cleaning operation of the
apparatus utilizing water and a chemical cleaning agent is made
impossible; the axis is caused to be locked; and a failure in the
driving device is made to occur, would be caused. To overcome these
problems, it has been desired that a method and an apparatus as
used in the present invention be provided, in which method, the
driving device for the turntable is not positioned at the bottom
surface of the heating chamber, and which apparatus can be
disassembled for ordinary cleaning and operates perfectly.
A most typical turntable has an entirely flat form, and is
supported by a rotational axis at the center thereof. The turntable
itself has a latticed construction so that the food products can be
effectively impinged on by the jet of heated air and microwaves.
However, the area around the center of the turntable cannot be
sufficiently heated due to the lack of the heating by the
impingement of the heated air jet and the microwaves.
Accordingly, there has been provided a prior art apparatus having a
heating mechanism made more effective due to its improved turntable
mechanism, in which apparatus, for example, a turntable has an
opening at the central part thereof and is supported by four roller
legs. These legs are positioned at periphery portions of the
turntable. In such a structure, the problem of the previously
mentioned prior art has been overcome by means of supporting the
turntable at the periphery portions thereof, so that the heated air
and microwaves can impinge on the area about the center of the
turntable. In such a structure, however, since the rotation of the
turntable is allowed by means of the engagement between the
supporting rollers and the outer periphery of the turntable, a new
problem might arise when the engagement is made ineffective by
imposing an eccentric load on the turntable, thereby causing a
failure of the engagement. Thus, another new problem, namely, the
turntable cannot rotate smoothly, arises. Accordingly, it is
desirable to provide a structure whose heating mechanism has been
improved, without, as a result, the turntable rotation being
hindered.
In connection with the rotation of the turntable, it is necessary
to consider the overloading problem caused at the time the
turntable rotates. Since the turntable is constructed to be rotated
by rotation torque transmitted to the turntable, which torque is
generated by a motor positioned at the outside of the oven, it
sometimes happens that large overload is applied to the driving
motor due to a locking of the rotating axis which is caused by
contaminants attached to the axis, or an obstruction to the
turntable rotation which is caused by contaminants interposed
between the turntable and, for instance, an inside wall of the
oven, such an interposition being possibly caused by, for example,
any incorrect management. There is a method of stopping the motor
as a way to protect the driving motor from having such an overload
applied thereto, in which method an electric current value
(electric signals) in the motor is detected or an increase in the
temperature in the motor is detected, so as to stop the motor when
it is overloaded. However, if the motor is a relatively small one,
such detections might be often difficult to accomplish. Thus, there
is a need to provide a mechanical torque limiter mechanism, a
further need that such a mechanism be smaller and more precise in
function than the torque limiter mechanism in the prior art, and
lastly that it not require any maintenance.
The heating mechanism of the turntable can be improved by utilizing
the jet impingement technique. In the jet impingement technique,
the heating operation (heat transmission) can be performed in a
shorter time and more effectively than that of the prior art, since
the heated air is impinged at a high speed on the objects to be
heated. Also, it takes only a short time to properly color the
surfaces of such objects by baking. However, since the heat
conductivity of the impinged jet of the heated air is very large,
the magnitude of the heat conductivity in the parts of the food on
which the jet of the heated air is impinged may vary depending on
the jet speed at each of the ejector pores of the jet (correctly
referred to as "Reynolds numbers"), where the greater the jet speed
is, the greater the heat conductivity is. Accordingly, when the jet
impingement technique is utilized, the difference between the parts
of the food well heated and the parts not well heated is increased,
compared with the typically used heating method. Thus, unevennees
in the "baking finishing" is caused to the food product to be
heated, when parts of the food are well heated and others are not
well heated, and when there are differences in the velocities of
the jet speeds. Thus, it is required to make the flow speed at each
of the ejector pores of the jet the same and effective, so as to
give a beautiful appearance to the baked food without unevenness
due to the baking.
In a prior method, a duct is provided in the oven, the duct having
a width tapered from its upper side to lower side in a direction
along the air flow, and being provided with a plurality of ejectors
on one side of the upper surface and one side of the lower surface
of the duct. However, such a structure makes the structure of the
apparatus complicated, and thus the cleaning operation is not easy.
Thus, it has been desired to provide a more simplified structure,
having a smaller number of components, thus making the cleaning
operation easy, and making the jet speed of the heated air
uniform.
In addition to function problems, a safety problem may arise in the
oven. Since the fan and the heater are often disposed in the
interior of the heating chamber, it is required to prevent the user
from injuring his fingers by touching the rotating fan and the
heater when he puts materials to be heated, such as food, into the
oven or take it out therefrom.
In the prior apparatus, an apparatus has been provided comprising a
structure which activates a door switch (a micro switch is
typically used) when the door is opened by the users, so that the
rotation of the fan motor can be stopped. If such an apparatus is
used for an apparatus whose door is very frequently opened and
closed, in particular, when it is used for the purpose of obtaining
quick service, the fan of such an apparatus may be frequently
stopped, thus causing problems in performance, function, and
durability. A fan guard is typically provided in front of the fan
and the heater, so as to prevent the user from touching them. In
this case, it is desirable to make it possible to remove the fan
guard from the heating chamber, so that the cleaning performance
can be improved, and also the fan guard can be taken out from the
heating chamber at the time of cleaning. In an oven also utilizing
microwave heating, the fan guard is often adapted to function as a
shield board against microwaves. In this situation, since it is not
easy to remove such a fan guard, and thus the cleaning performance
is not always good, it has been desired to improve the oven by
adapting a part other than the fan guard to have it a function as a
shield board, so that the fan guard can be removed from the heating
chamber for baking using a strong flame.
However, when the fan guard is made removable, it sometimes happens
that the oven will be used under such a condition that it is
forgotten to reset the fan guard in the heating chamber after its
cleaning operation is finished. Thus, there is a possibility that
the fan will be activated without re-setting the fan guard, and as
a result, the user might be injured by the rotating fan and the
heater when his fingers are inserted into the heating chamber.
Also, there is a possibility that the fan and heater may be
activated in error, while an operation for resetting the cleaned
fan guard in the heating chamber is being performed. Thus, it has
been desired to provide the fan guard which is not only removable
from the apparatus, but prevents the user from forgetting to reset
the fan guard.
The efficient utilization of space is an important subject which
not effects more than just the heating apparatus. In the prior art,
for instance, there is an apparatus having an exhaust tube for
exhausting various gases, such as water, smoke, and so on, to the
outside of the heating chamber, the gases being generated in the
heating chamber at the time of cooking the food in the heating
chamber of the oven. The apparatus of this type is provided with a
door at the front side of the exterior cladding of the body, the
food being put into the heating chamber or taken out therefrom when
the door is open. The apparatus of this type is further adapted to
have exhaust tubes and so on, which protrude from the interior of
the heating chamber to the rear side of the back board of the
exterior cladding, so the gases in the heating chamber are
exhausted to the outside thereof. Thus, in the prior apparatus of
this type, the exhaust tube is protruded from the back board of the
exterior cladding to the rear side of the heating apparatus, the
heating apparatus is limited to being put in a place separated from
the backside wall of the oven by a predetermined distance when it
is used.
When this apparatus is used in business, the cost performance can
be significantly improved, since this apparatus makes it easy to
realize a system of many apparatuses put in one place rather than
putting one apparatus in one place, which system can respond to
successive cooking orders just-in-time. In this case, to
effectively utilize space and labor, the heating apparatuses are
often stacked upon one another. Therefore, there is a need to
connect the exhaust tubes of the heating apparatuses together, in
such a way that the exhaust tube in a lower part of the stack and
one in an upper part of the stack do not overlap one another, at
the outside of the heating apparatuses. This worsens the external
appearance of the apparatus; makes it necessary to place a heat
barrier around the exhaust tubes and to provide safeguards; and
makes it necessary that an excessive space for setting the
apparatuses be provided. Accordingly, it has been desired to
provide an apparatus which overcomes these problems, so as to
enable the apparatuses to be stacked in a narrow space in order to
improve the efficient utilization of space; and which makes it easy
to maintain and manage such an apparatus.
SUMMARY OF THE INVENTION
As mentioned above, as with other kinds of apparatuses, there are
many problems to be solved concerning the heating apparatus. The
present invention has inclusively studied the above problems to
provide approachs therefor.
According to the present invention, a turntable mechanism is
provided, which mechanism comprises: a central support axis
positioned within a heating chamber of a heating apparatus which
provides hot air heating and micro-wave heating; a turntable of
which a central portion is supported by said central support axis,
so as to rotate the turntable around the axis; and a driving means
for rotating the turntable; wherein said turntable has an entirely
flat shape and includes a plane on which food products to be heated
can be mounted, a central portion of the flat shape portion being
formed into a concave downwardly recessed into the plane so as to
be fixed to and supported by the central support axis, said plane
and concave of the flat shape portion having a plurality of
openings for passing through hot air and the micro-waves, and said
driving means being engaged with an outer periphery of the flat
shape portion so as to transmit the rotating torque to the flat
shape portion. Thus, improvement of the heating function can be
accomplished without causing any trouble regarding the rotation of
the turntable itself.
Also, in accordance with the present invention, the turntable is
rotated by engaging a turntable driving wheel-gear with teeth which
are provided at the outer periphery of the turntable, so as to
transmit the rotating torque from the turntable driving gear-wheel
to the turntable. The turntable gear-wheel is positioned in the
corner of the interior of the heating chamber, and is vertically
suspended from the ceiling surface of the heating chamber by
utilizing a rotating axis penetrating through the axis receptor
attached to the ceiling surface of the heating chamber. Thus, the
cleaning operation for the heating chamber utilizing water and
detergent can be simplified, because the cooking and cleaning
operations are not interrupted, and water, oil and juice from the
food product does not drop from the axis receptor, thus preventing
any troubles regarding the driving portion from occurring. Also,
according to the present invention, the air pressed by the fan is
introduced into the inside of the axis receptor and a small amount
of air is always made to flow into the side of the heating chamber
via a gap between the axis receptor and the axis, so as to prevent
contaminants and detergent from flowing upwardly into the gap
between the axis receptor and the axis, due to operations such as a
respiration operation caused by fluctuations in pressure between
the inside of the heating chamber and the side of the axis receptor
upon repeating the heating and cooling operations in the heating
chamber; and a capillarity operation caused by the osmotic power of
the detergent, such as a surface active agent, and the small gap
between the axis receptor and the axis.
Further, in accordance with the present invention, a turntable
apparatus comprising a torque limiter is provided, the turntable
apparatus comprises a turntable; a driving source for rotating the
turntable; a turntable driving system driven by said driving
source; and a turntable driven system engaged with said turntable
driving system to rotate the turntable; wherein the turntable
driving system includes a means for breaking the engagement between
the turntable driving system and the turntable driven system, so as
to remove thrust load applied from the turntable driven system to
the turntable driving system when overload is imposed on the
rotation of the turntable.
Further, in accordance with the present invention, the present
apparatus is provided with boards on both the ceiling surface and
the bottom surface of the heating chamber, the boards having a
plurality of jet ejectors which are referred to as jet plates, so
that the heated air generated by means for generating heated air,
positioned in a rear side (the interior) of the heating chamber
,can be guided to a cooking chamber area in the front part of the
heating chamber and made to flow out as a jet impingement to the
food products on the above mentioned turntable, the jet flow
finally being made to impinge onto the food to be heated. Parts
surrounded by each of the jet plates, the ceiling surface, and the
bottom surface of the heating chamber form a passage for the heated
air, and the passage, as seen in a side cross sectional view
thereof, becomes more tapered in a direction from the rear side
(the interior) to the front side of the heating chamber. By means
of the above construction, the direction of the heated air flowing
in a horizontal direction is gradually changed by up to 90.degree.,
so that the heated air finally flows to the food products on the
turntable in a vertical direction, such a changing of the flow
direction enabling the heated air from the plurality of ejecting
pores to effectively provide heat and to flow at a uniform rate.
The passage for the heated air is formed by the above mentioned jet
plates and recesses on the ceiling and the bottom surfaces of the
heating chamber, the recesses being provided with scarfed areas to
form the tapered passage. Thus, the present invention realizes a
heating chamber having a simplified and very good cleaning
operation and also having a good heating performance without the
need to use other elements which may cause problems regarding the
cleaning operation.
Also, the recess having the scarfed area at the bottom of the
heating chamber can be used, upon cleaning the heating chamber, to
reserve water therein, the water being heated by the microwaves and
an electric heater on the backside of the bottom of the recess, so
as to generate vapor. Thus, contaminants attached onto the wall
surface of the heating chamber can be easily cleaned away by vapor
power as well as chemical power, and further, the recess can be
utilized, upon cleaning the heating chamber, to temporarily reserve
the exhaust water therein, the exhaust water being mixed up with
the water and the detergent for cleaning away contaminants, without
allowing the exhaust water to freely flow out from the front side
of the heating chamber. If it is required to drain the exhaust
water from an exhaust overflow, the exhaust water may be easily
drained by providing such exhaust overflow to the recess. Thus, a
great improvement in cleaning performance has been achieved, and
further, if the components in the front side of the heating chamber
(cooking chamber) can be made to be removable ones, the heating
apparatus having an improved cleaning performance can be
provided.
Also, in accordance with the present apparatus, a heating apparatus
is provided, comprising a switch activation means forming an
interlock circuit. When the fan guard of the present invention,
which is removably fixed to the inside of the heating chamber in
front of a means for transmitting the heated air into the heating
chamber, is positioned at a predetermined place in the heating
chamber, the interlock circuit accurately senses the positioning of
the fan guard as the interlock circuit is not effected by the
contaminants and temperature in the heating chamber, and without
the need to provide any attachments at the outside of the heating
chamber, and then activates a switch to allow the generation of the
heated air.
Further, in accordance with the present invention, a heating
apparatus is provided, which apparatus is provided with, at a part
of a exterior cladding of the apparatus body, an exhaust dividing
chamber penetrating the apparatus between the upper and the lower
sides of the apparatus, and an exhaust tube connected to a heating
chamber, the tube extending to the upper side of the apparatus via
the exhaust dividing chamber, so as to exhaust smoke and
unnecessary vapors and so on from the tube, which are generated at
the time of cooking. Wherein, upon a plurality of these heating
apparatuses being stacked, the exhaust tubes can be connected and
extended within the exhaust dividing chambers, so that harmful
smoke, vapors, heated air and so on, can be guided to the apparatus
at the highest stage of the stack of the apparatuses.
BRIEF DESCRIPTION OF THE DRAWINGS
The above and related objects, features and advantages of the
present invention will be more fully understood by reference to the
following detailed description of the preferred embodiments of the
present invention when taken in conjunction with the accompanying
drawings wherein;
FIG. 1 illustrates a perspective schematic illustration of the
heating apparatus in accordance with one embodiment of the present
invention.
FIG. 2 illustrates one example of the structure for the heating
chamber of the heating apparatus in FIG. 1.
FIG. 3 is a sectional view taken along line I--I of the heating
apparatus in FIG. 1.
FIG. 4 is a sectional view taken along line II--II of the heating
apparatus in FIG. 1.
FIG. 5 is a sectional view taken along line III--III of the heating
apparatus in FIG. 1.
FIG. 6 is a sectional view taken along the line II--II of the
heating apparatus in FIG. 1, comprising the torque limiter
mechanism,
FIG. 7 illustrates only a portion of the turntable driving
mechanism of the heating apparatus in accordance with one
embodiment of the present invention.
FIG. 8 illustrates the torque limiter mechanism in a normal
condition, which is provided in the turntable driving mechanism in
FIG. 7.
FIG. 9 illustrates the torque limiter mechanism in an active
condition provided in the turntable driving mechanism in FIG.
7.
FIG. 10 is a diagram explaining how the torque limiter mechanism in
FIG. 8 and FIG. 9 is activated.
FIG. 11 is a sectional view taken along the line I--I of the
heating apparatus in FIG. 1 provided with a microwave heating
device.
FIG. 12 is a sectional view taken along the line II--II of the
heating apparatus in FIG. 1, after the components within the
heating chamber have been removed.
FIG. 13 illustrates the heating apparatus in FIG. 12, comprising
the microwave heating device, the bottom thereof reserving water
therein.
FIG. 14 is a perspective schematic illustration of the fan guard in
accordance with one embodiment of the present invention.
FIG. 15 is a partly sectional fragmentary view of the fan guard in
FIG. 14 as seen from the direction of the arrow "A" thereof.
FIG. 16 is a partly sectional fragmentary view of the fan guard in
FIG. 14 as seen from the direction of the arrow "B" thereof.
FIG. 17 is an enlarged view of the fan guard in FIG. 14 as seen
from the direction of the arrow "C" thereof.
FIG. 18 is a sectional view taken along the line I--I of the
heating apparatus in FIG. 1 provided with the fan guard in FIG.
14.
FIG. 19 is a sectional view taken along the line III--III of the
heating apparatus in FIG. 1 provided with the fan guard in FIG.
14.
FIG. 20 is a perspective view of the heating apparatus in
accordance with the present invention having the exhaust pipe.
FIG. 21 is a partially cutaway perspective view of the heating
apparatus in FIG. 20 as seen from the rear side thereof.
FIG. 22 is a partially cutaway perspective view of the heating
apparatus in FIG. 20, in which three such apparatuses are stacked
upon one another.
FIG. 23 is a partially cutaway perspective view of the heating
apparatus in FIG. 22, in which three such apparatuses are stacked
upon one another.
FIG. 24 illustrates only a turntable driving mechanism of the
heating apparatus in accordance with one embodiment of the present
invention.
FIG. 25 is a partially enlarged sectional view of the turntable
driving mechanism in FIG. 24.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
With reference to the drawings attached to the specification,
embodiments of the present invention will now be described in
detail.
FIG. 1 illustrates a perspective view of the heating apparatus of
the present invention. FIG. 2 illustrates a configuration of the
heating chamber of the heating apparatus. Each of FIGS. 3 to 5
illustrates a sectional view of the heating apparatus in FIG. 1
taken along the lines I--I, II--II, and III--III, respectively.
As is clearly shown in FIG. 2, the heating chamber 1 chiefly
comprises an upper board 2, a lower board 3, a back board 4, and a
front board 16 of the heating chamber.
The back board 4 has a spiral shape which includes air plenums on
the upper side and lower side thereof. A fan 5 and a heater 6 are
provided in front of the back board 4, and a fan motor 7 for
providing the rotating torque to the fan 5 is provided behind the
same. The heater 6 is wound into a coil shape and is set in the
center of the fan 5 which is positioned at the center of a spiral
chamber, so as to reduce air resistance.
The heating chamber 1 is separated by a fan guard 8 into a cooking
chamber 9 and a spiral chamber 10. The center part of the fan guard
8 is shaped into a bell-mouth, so as to make the resistance caused
by sucking air small. Also, in order to reduce the air resistance
caused by blowing out the air, an air blower has been R-bended at a
front end thereof.
The spiral chamber 10 is provided with air plenums on upper and
lower sides thereof for transmitting the heated air produced by a
combination of heat generated by the heater 6 and wind produced by
rotating the fan 5. The heated air blown away from the upper and
lower sides of the spiral chamber 10 passes through scarfed areas
of the upper board 2 and the lower board 3, and then is guided to
an upper jet plate 11 and a lower jet plate 12 on the front side of
the heating chamber, and finally blown to the heating chamber 1 as
a high velocity wind from a plurality of jet valves 19 provided in
the upper and lower boards 11, 12.
To accomplish a uniform heating of the food product 17 to be
heated, a turntable 13 must be rotated at a predetermined speed
during the heating process. A turntable motor 18 which is fixed to
a gear box 30 by a turntable motor fixing leg 28 (shown in FIG. 6)
generates a torque for rotating the turntable 13.
A turntable axis 14 is fixed to the central part of the lower jet
plate 12 to rotate the turntable 13 around the axis. The turntable
13 has a generally planar shape. To rotate the turntable 13
smoothly, a turntable axis receptor 97 (as shown in FIG. 3) is
fixed to the central part of the turntable 13. Teeth 96 are engaged
with a gear-wheel 15 for driving the turntable, so that the
rotating torque is transmitted to the turntable 13, the teeth being
separated into many parts of the same size and provided at the
outside periphery of the turntable 13.
The gear-wheel 15 is suspended by a connecting shaft 21 and a
connecting shaft receptor 91. A
left-twisted-spiral-miter-gear-wheel 31 is fixed to the front end
of the connecting shaft 21. The
left-twisted-spiral-miter-gear-wheel 31 is engaged with a
right-twisted-spiral-miter-gear-wheel 32 in such a direction that
the left-twisted-spiral-miter-gear-wheel 31 is perpendicular to the
direction in which the connecting shaft 21 extends. The
left-twisted-spiral-miter-gear-wheel 31 receives the rotating
torque generated by the turntable motor 18 via the
right-twisted-spiral-miter-gear-wheel 32.
The food product mounted on the turntable 13 is impinged by a jet
of the heated air, generated from the jet valves 19 on the upper
and the lower jet plates 11, 12, and thereby rapidly heated. The
jet valves 19 are preferably arranged in such a way that the entire
surface of the plane on which the food product is to be mounted,
can be definitely exposed to the jet of the heated air from any of
the jet valves upon a rotation of the turntable 13.
(Turntable Mechanism)
As clearly seen in FIG. 5, in accordance with the present
invention, a plane of the turntable 13 on which the food product is
mounted is provided with many openings 94, so as to allow the
heated air and the microwaves to pass through these openings.
Further, referring to FIGS. 3 and 4, the central part of the
turntable 13 has a recess 95 downwardly concaved against the plane
on which the food product is mounted, and arranged to be fixed to
and supported by the turntable axis 14, the recess 95 also being
provided with openings. Thus, the food product is directly impinged
by the jet of the heated air from the lower side of the turntable
13 passing through these openings 94. As a result, according to the
present invention, even the central part of the turntable 13 may be
effectively heated by the heated air.
The heating operation can be effectively accomplished, even when
such an operation is performed in combination with microwave
heating, since the microwaves can pass through the openings 94 in
the turntable 13 from the lower side thereof to the food product
17.
(Torque Limiter Mechanism)
FIG. 6 is a sectional view taken along the line II--II of the
heating apparatus in FIG. 1 having the torque limiter mechanism.
Further, each of FIGS. 7 to 9 illustrates a turntable driving
mechanism for transmitting the rotating torque generated by the
turntable motor 18 to the turntable 13, respectively.
The gear wheel 15 for driving the turntable 13, which is engaged
with the teeth 96 provided at the outside periphery of the
turntable 13, is connected to the connecting shaft 21, the shaft 21
being further connected to the connecting shaft 22. The front end
of the connecting shaft 21 and that of the connecting shaft 22 are
fixed to the right and left-twisted-spiral-miter-gear-wheels 31,
32, respectively, these gear wheels 31 and 32 being engaged
together to be perpendicular to each other.
An axis receptor 37 for receiving the connecting shaft 21 is fixed
to the upper side of the heating chamber 1 by using an axis
supporter 40, to rotate the connecting shaft 21 at the inside of
the axis supporter 40. The connecting shaft 22 is adapted to rotate
between two connecting shaft receptors 38 positioned at the gear
box 30. In normal conditions, the connecting shaft 21 is rotated
due to the engagement between the left and
right-twisted-spiral-miter-gear-wheels 31, 32.
A connecting pin 24 is inserted along a motor direction, at one
side opposite to the left-twisted-spiral-miter-gear-wheel 32 which
is fixed to the front end of the connecting shaft 22. The
connecting pin 24 also serves as a stopper. The connecting shaft 22
is adapted to slide on the inside of a connecting shaft joint 23 in
a horizontal direction, which joint is cut into a groove shape,
while the front end of a shaft for the motor 18 is fixed to the
inside of the connecting shaft joint 23.
A pressure coil spring 25 is positioned in the gap between the
connecting shaft joint 23 and the motor 18, where, since in the
normal condition, the pressure coil spring 25 is expanded, the
rotating torque from the motor 18 will be effectively transmitted
from the connecting shaft 22 to the mechanism to be driven.
Upon the turntable 13 being overloaded due to any cause, a thrust
load directed in the direction as indicated by an arrow in FIG. 8
will be generated between the right-twisted-spiral-miter-gear-wheel
32 and the left-twisted-spiral-miter-gear-wheel 31. Even when the
thrust load is generated, when a pressure generated by the pressure
coil spring 25 is stronger than pressure strength of the thrust
load, the rotating torque of the motor 18 can be properly
transmitted to the turntable driving gear wheel 15. FIG. 8
illustrates this condition.
The pressure coil spring 25 will be pressed toward the motor 18,
when the pressure strength of the thrust load becomes larger than
the pressure from the pressure coil spring 25, due to the
imposition more than a predetermined quantity of overloading on the
turntable 13 or the locking of the turntable 13 for any reason.
FIG. 9 illustrates this condition.
Referring now to FIG. 9, the pressure coil spring 25 will be, in
this case, pressed so that the
right-twisted-spiral-miter-gear-wheel 32 is rotated without
engaging with the left-twisted-spiral-miter-gear-wheel 31. As a
result, the motor 18 is prevented from being directly loaded, that
is, an overloading removing mechanism or the torque limiter
mechanism will act effectively.
Accordingly, the present invention provides the torque limiter
mechanism for mechanically releasing the engagement between the
turntable driving mechanism and the turntable driven mechanism.
(Jet Impingement Mechanism)
In connection with FIGS. 3 to 5, the heating apparatus using a jet
impingement technique of the present invention will be described
below. Each of the upper and lower jet plates 11, 12 comprises a
plurality of impingement pores each having a nozzle shape, so that
the heated air guided via the scarfed areas of the upper and lower
boards 2, 3 can be changed to an ultra-high speed jet, after
passing over these areas.
Now, according to the heating apparatus of the present invention,
one part of each of the upper and lower boards 2 and 3 is comprised
of a scarfed area, a cross-sectional view of which is tapered in a
direction from the rear side to the front side of the heating
chamber 1. A front end of each of the scarfed areas has a -shape
27, so as to reduce the amount of air generated by the fan 5 and
leaking from the clearances between the front ends of the upper and
lower jet plates 11, 12 and the wall surface of the heating
chamber. A rectification board 34 is provided to change the air
flow generated by the fan 5 into a layer flow, so as to reduce air
pressure loss.
The scarfed areas provided on the upper board 2 and the lower board
3 form the heating chamber 1, and also act as passages for the
heated air generated by means of the fan 5 and the heater 6. By
providing such scarfed areas, the velocity of the heated air
flowing from a plurality of jet impingement pores on the upper and
the lower jet plates 11, 12, is made uniform.
The components, such as the upper jet plate 11, lower jet plate 12,
fan guard 8, turntable axis 14, turntable driving gear wheel 15 and
so on, can be simply secured to and removed from the body. For
example, the fan guard 8 can be easily positioned between portions
of the inner wall surface of the heating chamber 1 by pushing end
edges of the fan guard. The upper jet plate 11 and the lower jet
plate 12 can be easily positioned between the inner wall surface of
the heating chamber 1 and a wall of the fan guard 8 by pushing end
edges of the plates 11 and 12. Also, the turntable 13 can be
removed from the turntable axis 14. The turntable axis 14 is
removable, as is the lower jet plate 12, and the turntable driving
gear wheel 15 is adapted so that the axis of the connecting shaft
21 is easily fitted into the center thereof.
As shown in FIG. 12, upon removing all the above components, only
the fan 5, heater 6, and rectification board 34 would be left in
the heating chamber 1, . Accordingly cleaning performance of the
heating chamber 1 can be enhanced. Referring now to FIG. 13, by
reserving water and detergent 52 at the recess at the scarfed area
of the bottom part of the heating chamber 1 and then heating these
by means of microwaves and an electric heater (not shown) provided
behind the bottom surface of the heating chamber 1, so as to change
the water and the detergent into vapor, contaminants attached to
the wall surfaces of the heating chamber 1 can be made easy to
clean away by means of the vapor power.
FIG. 11 illustrates a sectional view taken along a line I--I of the
heating apparatus in FIG. 1, the apparatus additionally comprising
a microwave heating device used as a heating source. A waveguide 35
is attached to the upper side of the heating chamber 1 to transmit
the microwaves to the heating chamber 1, the microwaves is
generated by a microwave generator 36 at the end of the heating
apparatus. A cover 51 provided at the front end portion of the
waveguide 35 on the side of the heating chamber 1 is made from
materials having a small dielectric loss coefficient, so as to be
able to prevent heated air and gas generated by the food product
from entering into the waveguide. If the material of the upper jet
plate 11 is made from small dielectric loss coefficient materials,
an opening of the waveguide 35 can be positioned at the upper
surface of the upper plate 11 of the heating chamber 1.
(Fan Guard)
FIGS. 14 to FIG. 17 illustrate a heating apparatus having a fan
guard of the present invention. FIG. 14 is a perspective, schematic
illustration of the fan guard according to one embodiment of the
present invention. FIG. 15 is a partly sectional fragmentary view
of the fan guard in FIG. 14 as seen from the direction of an arrow
"A" in FIG. 14. FIG. 16 is a partly sectional fragmentary view of
the fan guard in FIG. 14 as seen from the direction of an arrow "B"
in FIG. 14. FIG. 17 illustrates an enlarged view of the fan guard
in FIG. 14 as seen from the direction of an arrow "C" in FIG.
14.
As seen from these Figures, the fan guard comprises a fan guard
plate 41, having a spiral shape so as to define a circulation wind
air plenum at two places between an upper inside wall and a lower
inside wall of the heating chamber 1, when the fan guard plate 41
is attached to the inside of the heating chamber 1. A bell mouth
member 53 is formed at the center of the fan guard plate 41 for
sucking air. Further, a fan guard net 42, parts of which are
appropriately separated from each other, is attached to an opening
of the bell mouth 53 of the fan guard plate 41, so as to prevent a
user from inserting in error his hand or fingers into the
opening.
A holder rail 46 is attached to the lower side of the fan guard
plate 41. The holder rail 46 is made of a metallic tube and is
provided with an axis receptor 48 at the inside of the front end
portion thereof. As clearly shown in FIG. 14, a guide fixing groove
46A having an almost L-shape is formed at the outside periphery of
the metallic tube of the holder rail 46. A magnet holder 45 is
secured to the holder rail 46 in such a way that the holder can be
moved along the inside of the axis receptor 48 of the holder rail
46. The front end portion of the magnet holder 45 is provided with
a magnet 43 made from rare earth elements having a good
demagnetizing characteristic at a high temperature. The magnet 43
is accommodated in a magnet case 44 for protecting the magnet 43
from being damaged, and concentrates a magnetic flux on the front
end portion of the magnet holder 45.
A holder lug 47 is provided near the end of the magnet holder 45
opposite to the end on which the magnet 43 is attached. The magnet
lug 47 is projected to the outside of the holder rail 46 through
the L-shape guide fixing groove 46A formed in the holder rail, so
as to enable the user of the heating apparatus to operate the
magnet holder 45 by hand. As shown in FIGS. 14 to FIG. 16, when the
holder lug 47 is positioned in a groove portion corresponding to a
shorter leg of the L-shaped guide fixing groove 46A, the magnet
holder 45 is fixed in position so that it can not be moved in
either a right or left direction. To move the magnet holder 45
under such a fixed condition, the holder lug 47 must be operated to
rotate the magnet holder 45 in the axis receptor 48, so as to move
the magnet lug to a groove position corresponding to a longer leg
of the guide fixing groove 46A, and further move it in the left
direction in the Figures along the longer leg of the groove 46A,
thereby moving the magnet holder 45 in a left direction which
results in the movement of the magnet 43 from a fixed position to a
pulled back position. To move the magnet 43 from the pulled back
position to the fixed position as shown in FIG. 14 to FIG. 16, an
operation the reverse of the above is used.
FIG. 18 is a sectional view taken along the line I--I of the
heating apparatus in FIG. 1, comprising the fan guard of the
present invention. FIG. 19 is a sectional view of the heating
apparatus, taken along the line III--III. Referring now, in
particular, to FIGS. 18 and 19, a description will be given of an
operation for fixing the fan guard as explained in connection with
FIG. 14 to FIG. 17 of the invention at a predetermined position
within the heating chamber of the heating apparatus. The fan guard
can be removed from the front side of the heating chamber 1 of the
heating apparatus. Upon setting and removing the fan guard, the
holder lug 47 is operated to slide the magnet holder 45 into the
pulled back position thereof, so that the magnet case 44
accommodating the magnet 43 can be moved to be in a plane of the
fan guard plate 41.
In an inner part of the heating chamber 1, the fan 5 driven to be
rotated by the fan motor 7 is positioned. The heater 6 is disposed
at the inner periphery of the fan 5. The fan guard 8 is removably
positioned at the front portion of the fan 5 within the heating
chamber 1. To accomplish this, a fixing pin 62 is provided on the
upper portion of the side wall of the heating chamber 1, and a
magnet case guide 49 is provided on the lower portion thereof. The
magnet case guide 49 is embedded in a thermal insulant 57, so as to
prevent the atmosphere in the heating chamber 1 from leaking
out.
The magnet case guide 49 has a tube shape of which a front end
portion is closed, the tube shape enabling the magnet case 44 to be
fit into the magnet case guide 49, the magnet case 44 being
attached to the front end portion of the magnet holder 45 of the
fan guard 8. A magnet close switch 50 is fixed, at the outside of
the heating chamber 1, to a portion apart by a predetermined
distance from a front end portion of the magnet case 44. The
magnetic close switch 50 may be connected to an electric circuit
for applying electrical power to the fan motor 7 and the heater 6,
and be designed to be almost opened, but then closed when the fan
guard is fixed to the inside of the heating chamber 1, thereby
sliding the magnet holder 45 to insert the magnet case 44 into the
magnet case guide 49.
The fan guard 8 can be mounted on and fixed to a predetermined
position in the heating chamber 1, by setting the fan guard at the
predetermined position in front of the fan 5 in the heating chamber
1, engaging the upper portion of the fan guard plate 41 to the pin
62 provided on the inside wall of the heating chamber 1, and then
sliding the magnet holder 45 from the pulled back position, so as
to fit the magnet case 44 into the magnet case guide 49. Thus, the
holder rail 46, axis receptor 48, magnet holder 45, magnet 43 and
magnet case 44, mounted on and fixed to the fan guard plate 41, can
partially constitute a means for fixing the fan guard to the inside
of the heating chamber 1.
Thus, in accordance with the fan guard of the present invention,
when the fan guard is properly fixed to the predetermined position
in the heating chamber 1, since the magnet close switch 50 is
closed by utilizing the activation of the magnet 43, the fan and
the heater will be correctly operated by switching on the electric
power for the electric circuit incorporating the fan motor and the
heater. On the other hand, since the magnet close switch 50 is
still kept open as long as the fan guard 8 is correctly fixed to
the predetermined position in the heating chamber 1, turning on of
the power source for the fan 5 and heater 6 will not cause the
activation of the fan 5 and the heater 6.
The magnet close switch 50 is positioned close to the magnet case
guide 49 which has a high temperature due to its nature. In this
embodiment, to prevent heat from being transmitted from the magnet
case guide 49, fresh air is made to flow out from the part between
the magnet case guide 49 and the magnet close switch 50. For the
configuration to accomplish the above function, a cooling fan 54 is
additionally provided for introducing the fresh air from a
plurality of intakes 59 opened at the bottom of the cladding 56,
passing the air between the magnet case guide 49 and the magnet
close switch 50, and finally exhausting the air to the outside
thereof via the fan 54. The fresh air is obtained from a plurality
of holes 58A, which holes are provided on a side surface of the leg
58 positioned at the bottom of the cladding 56. Thus,the leg 58 can
be positioned at more inner parts of the front side of the
apparatus body than the cladding 56, and thus make the operation
for obtaining the fresh air possible, even if the cladding 56 comes
in contact with another perpendicular wall.
As is clearly shown in FIG. 18, in a condition that the fan guard
is attached and secured to a predetermined position within the
heating chamber 1, the air plenums 61 for circulating wind are
defined at the upper and lower portions of the heating chamber 1.
Thus, when the fan 5 is driven to rotate it, the sucking air from
the bell mouth 53 of the fan guard plate 41 is heated by the heater
6 disposed at the central part of the fan 5, and thus the heated
air is blown away from the upper and the lower air plenum 61 into
the heating chamber 1. Also, as shown in FIGS. 18 and 19, to
insulate the heating chamber 1, the surrounding outside perimeter
of the heating chamber 1, except for the front end portion of the
magnet case guide 49, is covered with insulating materials 57. The
fresh air from the fresh air intakes 59 cools the surface of the
insulating materials 57 when it flows over the surfaces of the
materials.
The magnet case guide 49 makes it easy to insert and take out the
magnet case 44 thereinto or therefrom by having a diameter at its
opened side larger than that at its closed side at the front end.
In the embodiment above mentioned, while the magnet 43 has been
described as being used for a switch activator and the magnet close
switch 50 as being used for the heat air generator, they are not
limited to such applications, as any combination is all right if it
accomplishes the above same functions.
(Exhaust Tube)
Referring now to FIG. 20 and FIG. 21, the heating apparatus having
the exhaust tube of the present invention will be described below.
FIG. 20 is a perspective view of the heating apparatus according to
one embodiment of the present invention. FIG. 21 is a partially
cutaway perspective view of the heating apparatus in FIG. 20 as
seen from the rear side thereof. As shown in these Figures, the
heating apparatus of the present embodiment comprises a leg part 77
positioned at a lower portion of an exterior cladding 76, and a
door 78 positioned at the front surface of the heating apparatus,
the door 78 including a door handle 79.
As is clearly shown in FIG. 21, an exhaust sectional chamber 82
penetrating the heating apparatus between upper and lower sides
thereof, is defined at one of the corners in the rear side of the
exterior cladding 76. The sectional chamber 82 is defined by the
following steps: defining a square hole in a bottom board 81;
defining the leg 77 which has been bent along the square hole at
the bottom board of the apparatus body; providing a sectional board
75 for a heating room to partition therefrom part of the interior
of the heating room; and defining a square hole, which is similar
to the above one, at the ceiling of the exterior cladding 76.
The exhaust pipe 72 as used for the exhaust tube is prepared in
such a way that one end thereof is connected to the heating chamber
via a circular hole which is provided in an upper portion of the
sectional board 75, and another end thereof is extended so as to
provide an opening in the upper side of the heating apparatus by
passing through the sectional chamber 82. For the reasons as
mentioned below, the front end portion of the opening of the
exhaust pipe 72 should preferably be extended. An insulating
material 80 is wound around the exterior periphery of the exhaust
pipe 72 in the sectional chamber 82. As is clearly shown in FIG.
20, a portion 76A at the top of the exterior cladding 76 surrounds
the square hole of the sectional chamber 82, and has a -shape, so
as to prevent any contaminants on the top surface of the exterior
cladding 76 from entering into the sectional chamber 82.
Referring now, in particular, to FIG. 22 and FIG. 23, one example
of how the heating apparatus having the above configuration is used
will be described below. FIG. 22 is a partially cut away
perspective view of the heating apparatus explained in connection
with FIGS. 20 and 21, in which three of the above apparatuses are
stacked upon one another. FIG. 23 is a partially cut away
perspective view of the three heating apparatuses in FIG. 22
stacked upon one another. As is apparent from these FIGS. 22 and
23, by utilizing two S-shaped exhaust connecting pipes 73 and one
long liner exhaust connecting pipe 74, the exhaust pipe 72 extended
through a heating room 71 of a lower heating apparatus in the stack
can be guided to an upper square hole of the sectional chamber 82
of an upper heating apparatus in the stack, via the sectional
chamber 82 of a middle heating apparatus in the stack and the
sectional chamber 82 of the upper heating apparatus in the
stack.
Similar to the above, by utilizing the S-shaped exhaust connecting
pipe 73 and a liner exhaust connecting pipe 83, the exhaust pipe 72
connected to the heating room 71 of the middle heating apparatus in
the stack can be guided to the upper angular hole of the sectional
chamber 82 of the upper heating apparatus through the sectional
chamber 82 of the upper heating chamber in the stack. The exterior
peripheries of these pipes 73, 74 and 83 also have the insulating
material 80 wound thereon. Also, the periphery of the heating room
71 has the insulating material 80 wound thereon.
Thus, in accordance with the heating apparatus of the present
invention, even when these three heating apparatuses are stacked
upon one another within a projecting plane of these apparatuses, an
exhaust operation in the heating room 71 can still be preferably
managed. Further, since an upper end portion of the exhaust pipe 72
of the heating apparatus is widened to enlarge the diameter thereof
and also an upper end of the exhaust connecting pipe 73 is widened
to enlarge the diameter thereof, it is possible to prevent problems
such as leakage from the connecting parts between these pipes 72,
73, even when detergent is made to flow from the upper side of the
apparatuses to these pipes, at the time of washing the exhaust pipe
72 and the exhaust connecting pipes 73, 74 and 83.
(Turntable Driving Mechanism)
For simplification of understanding, FIG. 24 only shows a turntable
and a driving mechanism of the turntable relating to the present
invention.
The axis supporter 40 is fixed to an upper board 102 of the heating
chamber, to position the connecting shaft 21 at a predetermined
place. The upper board 102 is provided with a hole which the
connecting shaft 21 penetrates therethrough, and the connecting
shaft 21 passes through the penetrating hole, so that it can be
rotatably held between the exterior part and the inner part of the
heating chamber by utilizing the axis receptor 40. FIG. 25
illustrates an enlarged view of the axis receptor 40 and the
connecting shaft 21.
As will be understood from FIG. 25, the connecting shaft 21 has an
enlarged area 116 at the upper portion thereof. The
left-twisted-spiral miter-gear-wheel 31 is fixed to a projection
118 at the upper portion of the connecting shaft 21 so as to allow
the transmission of the rotating torque between the connecting
shaft 21 and the left-twisted-spiral-miter gear wheel 31. The
connecting shaft 21 is held at the lower portion of the enlarged
area 116 of the shaft 21 by utilizing a metal axis supporter 106
which is provided at the lower portion of the axis supporter 40, so
as to position the shaft at a predetermined height. The under side
surface of the enlarged area 116 is surrounded by a side wall 110
provided on the exterior side of the metal axis receptor 106. There
is no gap between the side wall 110 and the upper board 102.
The upper portion of the enlarged area 116 of the connecting shaft
21 is surrounded by a sleeve 112. A shielding member 104, which is
rotatably secured to the connecting shaft 21, is provided at the
inside of the upper end portion of the sleeve 112. There is a gap
between the sleeve 112 except for the upper end portion thereof and
the enlarged area 116. The exterior periphery of the sleeve 112 is
provided with a nut 108 fastened to the sleeve 112. A board 101 for
supporting the connecting shaft 22 is extended to the lower portion
of the sleeve 112 to fasten the nut 108 onto the extended portion.
There is no gap between the nut 108 and the supporting board 101.
The nut 108 sets the sleeve 112 at a predetermined position.
An air introduction opening 114 penetrating the nut 108 is provided
to transmit the air pressed by a fan (not shown) from the
introduction opening 114 to the inside of the axis receptor 40 via
a hose 115. Only such a fan is provided for the above use, however,
it is possible to also use for the above use a fan for cooling
components such as a magnetron. In other words, since the amount of
the air available for the above use is very small, it is possible
to introduce a part of the air generated by the fan, which is
provided for cooling the components such as a magnetron, into the
air introduction opening 114.
There is a relatively large gap between the axis receptor 40 and
the enlarged area 116 of the connecting shaft 21 to make it easy to
enter the air which is introduced from the air introduction opening
114 into the gap. The air introduced into the relatively large gap
is then guided to a lower part thereof along a lower part of the
enlarged area 116 and the side surface of the enlarged area 116,
and finally made to flow into the inside of the heating chamber
1.
Effect of the Invention
In accordance with the turntable mechanism of the present
invention, since the turntable is supported at the central portion
thereof and is rotated at the periphery thereof by the turntable
driving gear-wheel, the turntable can be preferably rotated even
when a food product is mounted close to the turntable periphery to
cause the turntable to be eccentrically overloaded. In addition,
since the turntable is provided with a concave at the central
portion thereof and further the concave is provided with openings,
hot air heating and microwave heating of the bottom of food product
to be heated which is mounted on the central portion of the
turntable can be effectively accomplished via the openings.
Further, since there is no rotating axis which penetrates the under
side of the heating chamber to transmit the rotating torque
therethrough, the cleaning operation utilizing water, detergent and
so on, is made easier.
The torque limiter mechanism of the present invention is provided
with a limiter mechanism, which can also be used in a small heating
apparatus, comprising a turntable that can hardly detect electric
signals, because the present apparatus utilizes only a mechanical
operation to detect and remove overloading, rather than detection
of the electric signals to detect the overloading.
In accordance with the jet impingement technique of the present
invention, the supplying of heated air is made uniform, since some
slopes are provided on parts of the ceiling and bottom surfaces of
the wall surfaces of the heating chamber, the slopes guiding the
heated air to the jet impingement ejectors. As a result, even if a
jet impingement technique is utilized, it is possible to achieve
more uniform and effective air heating, thereby making the baking
operation of the food product more uniform and effective. Further,
the structure of the present invention is simplified, since part of
the air passage to the jet ejectors is also commonly used as one
part of the heating chamber.
Further, since some of the components within the heating chamber
can be removed therefrom, improvement of cleaning performance can
be achieved. Also, an automatic cleaning operation can be improved,
since the water can be reserved in the recess formed by the scarfed
area at the bottom of the heating chamber.
The fan guard of the present invention is arranged to prohibit the
fan and the heater from being activated, when the fan guard is
still not firmly secured to the front face of the fan. Thus,
accidents to the hands, fingers and so on, can be avoided, which
accidents may occur due to the fan rotating at a high speed and the
heater being heated, under undesirable circumstance, to nearly
300.degree. C. and contaminants being generated in the inside of
the heating apparatus.
In accordance with the heating apparatus comprising the exhaust
tube of the present invention, it is possible to attach the
apparatus near a wall surface, since exhaust tubes can be easily
connected together within the heating apparatuses even when
stacking the heating appratuses one upon another. Further, it is
easy to clean the exhaust tube itself, and also no additional
components for heat shielding are required.
In accordance with the turntable driving mechanism of the present
invention, it is possible to effectively prevent contaminants and
so on, from flowing into the gap between the connecting shaft 5 and
the axis receptor 40, since it is possible for a small amount of
air to always flow from the outside to the inside of the heating
apparatus via the gap between the connecting shaft 5 and the axis
receptor 40, thereby eliminating obstacles which might hinder the
rotation of the connecting shaft.
* * * * *